KR20150045648A - Method and apparatus for transmitting and receiving a signal in a wireless communication system - Google Patents

Abstract

The present invention relates to a method and apparatus for transmitting and receiving a signal in a wireless communication system. Through the present invention, a receiver in the wireless communication system receives multiple signals from a transmitter using multiple antennas, estimates gains and departure angles for at least one among the multiple signals, sorts indexes for the multiple signals from the index with the largest signal gain, sorts data related to departure angles for each signal based on the sorted indexes from the data with the largest signal gain, and sends at least one among the data related to departure angles to the transmitter as feedback information.

Description

Field of the Invention [0001] The present invention relates to a method and apparatus for transmitting / receiving signals in a wireless communication system,

The present invention relates to a method and apparatus for transmitting and receiving signals in a wireless communication system.

When pre-coder techniques such as conventional ZF (Zero-Forcing) and RZF (Regularized Zero-Forcing) are used, the transmitter must acquire information about all channels used by each receiver. Therefore, in an environment where massive MIMO (Multiple Input Multiple Output) is easily used, such as a millimeter wave (mmWave) communication system, the burden of transmitting and receiving feedback information becomes large. In addition, as the power of a transmission signal is differently allocated to each antenna, a radio frequency (RF) -chain as many as the number of transmission antennas is required, and thus there is a problem in that it is costly in terms of hardware in the mmWave environment.

Considering such a problem, methods of using information such as a gain of a signal on an mmWave channel, an angle of departure (hereinafter referred to as 'AOD') and an angle of arrival (hereinafter referred to as 'AOA' Has been proposed. Among the above methods, there are a beam steering method and a null steering method as a representative method.

The beam adjusting method is a method in which a transmitter transmits a beam in a desired direction based on AOD information. However, since the beam adjusting method does not consider interference with other receivers, it can be effectively used in a single-user environment, but is not suitable in a multi-user environment. Therefore, when the beam adjusting method is used in a multi-user environment, the sum rate of the entire receiver is lowered.

On the other hand, the null adjustment scheme provides a interference control effect as a scheme for preventing a transmitter from transmitting a beam in an undesired direction based on AOD information. However, when the null adjusting method is used indiscriminately in a wireless communication environment in which multiple users and multiple signals are formed, there is a problem that transmission power must be amplified as nulls are formed in a similar direction.

The present invention proposes a method and apparatus for transmitting and receiving signals in a wireless communication system.

The present invention proposes a method and apparatus for controlling interference while reducing the amount of feedback information while using a smaller number of RF chains than the number of antennas in a wireless communication system.

Also, the present invention proposes a method and apparatus for improving the transmission rate while preventing the power amplification phenomenon of the null adjusting preprocessor in a multi-user mmWave environment.

The method proposed by the present invention comprises: A method of transmitting a signal of a transmitter in a wireless communication system, the method comprising: transmitting a plurality of signals to a receiver using a plurality of antennas; receiving information on angles of departure of at least one of the plurality of signals from the receiver The method comprising the steps of: determining a signal transmission direction based on the emission angle information; transmitting a signal using a predetermined transmission power in the determined signal transmission direction; wherein the launch angle information includes at least one of the plurality of signals arranged in descending order of the signal gain.

The apparatus proposed in the present invention comprises: A transmitter in a wireless communication system, comprising: a plurality of antennas; a transmitter for transmitting a plurality of signals to a receiver using the plurality of antennas; a transmitter for receiving at least one of the plurality of signals from the receiver, And a control unit for controlling the transmission unit to transmit a signal using a predetermined transmission power in the determined signal transmission direction, And a controller for performing null transmission in a signal transmission direction other than the signal transmission direction, wherein the emission angle information includes emission angle information for at least one of the plurality of signals arranged in descending order of signal gain.

The present invention can control interference while reducing the amount of feedback information while using a smaller number of RF chains than the number of antennas in a wireless communication system. In addition, the present invention has an advantage in that the transmission rate can be improved while preventing the power amplification phenomenon of the null adjustment type preprocessor in a multi-user mmWave environment.

FIG. 1 is a graph showing transmission power of each transmitter in a wireless communication system using a general null adjusting method,
FIG. 2 illustrates a wireless communication system according to an embodiment of the present invention; FIG.
3 is a block diagram of a transmitter and a receiver of a wireless communication system according to an embodiment of the present invention.
4 is a diagram illustrating a process in which a plurality of receivers according to an embodiment of the present invention transmit feedback information to a transmitter;
FIG. 5 is a graph showing transmission power of each transmitter in a transmission direction according to an embodiment of the present invention,
Figure 6 illustrates a baseband precoder and RF chain unit configured based on a null adjusting beam former in accordance with an embodiment of the present invention;
7 is a flowchart illustrating an operation of a receiver according to an embodiment of the present invention.
8 is a flowchart illustrating an operation of a transmitter according to an embodiment of the present invention.
9 is a graph illustrating performance according to an interference control method according to an embodiment of the present invention.

Hereinafter, the operation principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions of the present invention, and these may be changed according to the intention of the user, the operator, or the like. Therefore, the definition should be based on the contents throughout this specification.

The present invention provides a method and apparatus for interference control in a wireless communication system.

Prior to the description of the embodiments of the present invention, a null steering system generally used for interference control will be described.

)과 신호를 송신하기 원하지 않는 방향(

)을 동시에 고려하여 간섭을 제어하는 방식이다. 상기 송신기가 신호를 송신할 수 있는 각 방향을 어레이 벡터(array vector)를 사용하여 행렬 N으로 나타내면 다음 수학식 1과 같다.The null adjustment method is performed in a direction in which a transmitter desires to transmit a signal

) And the direction in which you do not want to transmit the signal (

) At the same time to control the interference. Each direction in which the transmitter can transmit a signal is expressed by a matrix N using an array vector,

If the matrix N is determined as described above, a null steering vector f may be determined based on the following equations (2) and (3).

In Equations 2 and 3, H denotes a Hermitian operation, and ⁺ denotes a pseudo inverse. In Equations (2) and (3), the transmission power of the first array vector is set to 1 and the remaining transmission power is set to 0, for example.

When the null adjustment vector is determined, the transmitter performs null transmission in the corresponding direction based on the determined null adjustment vector, and transmits the signal in the other direction. This will be described in detail with reference to FIG.

FIG. 1 is a graph illustrating transmission power of a transmitter according to a transmission direction in a wireless communication system using a general null adjustment method. Referring to FIG.

,

)(100, 120)을 결정한다. 그리고 상기 송신기는 상기 결정된 방향(

,

)(100, 120)에서 널 송신을 수행한다. In the graph shown in FIG. 1, the horizontal direction represents the angle of departure (hereinafter referred to as 'AOD'), and the vertical direction represents the transmission power. Referring to FIG. 1, when a null control vector is determined, the transmitter calculates a direction in which null transmission should be performed based on the determined null control vector

,

(100, 120). And the transmitter transmits the determined direction

,

(100, 120).

,

)(100, 120)을 제외한 나머지 방향 중 신호를 송신하기 원하는 방향(

)(140)에서는 가장 큰 송신 전력을 사용하여 신호를 송신한다. 여기서 상기 널 송신이라는 것은 송신 전력을 0으로 설정하는 것을 의미할 수 있다. In addition, the transmitter transmits the determined direction

,

) 100, 120 in the direction in which the signal is desired to be transmitted

) 140 transmits the signal using the largest transmit power. Herein, the null transmission may mean that the transmission power is set to zero.

In this way, the transmitter performs null transmission in an undesired direction and transmits a signal with a strongest intensity in a desired direction, thereby controlling the interference to other receivers so that a signal can be correctly transmitted to the receiver.

In the embodiment of the present invention, a scheme for improving a sum rate while preventing power amplification of a preprocessor in a multi-user millimeter wave (mmWave) communication environment using the null adjustment method present.

A wireless communication system according to an embodiment of the present invention is shown in FIG.

2 is a diagram illustrating a wireless communication system according to an embodiment of the present invention.

2, the wireless communication system may include a transmitter 200 and a plurality of receivers, for example, receiver 1 210, receiver 2 220, and receiver 3 230. The transmitter 200 may be a base station that transmits signals and the receiver 210, the receiver 220 and the receiver 230 may be mobile terminals receiving signals from the base station. The first receiver 210, the second receiver 220, and the receiver 3 230 are located at different positions. Therefore, the direction in which the first receiver 210, the second receiver 220, and the receiver 3 230 receive the signals transmitted by the transmitter 200 also must be different.

For example, the first receiver 210 may receive a signal transmitted in a direction of θ ₁ of the signals transmitted by the transmitter 200, and the receiver 220 may receive a signal transmitted from the transmitter 200 of which can receive a signal transmitted from the orientation θ _2, the receiver 3 230 can receive a signal transmitted in the direction θ ₃ of the transmitter 200 transmits a signal.

Accordingly, the transmitter 200 receives the feedback information including the AOD information or the like for each signal from each receiver, determines the direction to transmit the signal, and transmits the signal using the largest transmission power in the corresponding direction . In addition, the transmitter 200 can control the interference by using the null adjustment method and the like in the direction of interference with other receivers.

3 is a block diagram of a transmitter and a receiver of a wireless communication system according to an embodiment of the present invention.

FIG. 3 shows an example of a transmitter and a receiver included in the wireless communication system as shown in FIG. 3, each of the transmitter 300 and the plurality of receivers 320-1 to 320-K may perform communication using a plurality of antennas. Although not shown in FIG. 3, the transmitter 300 and the plurality of receivers 320-1 to 320-K each include a memory for storing various data and information generated by performing the wireless communication, And a controller for controlling the overall operation of each of the plurality of receivers.

The transmitter 300 has N _t transmit antennas and the plurality of receivers 320-1 to 320-K used by K users have N _r transmit antennas. The transmitter 300 has N _RF of radio frequency: may transmit a full-N _ts transmit streams through (Radio Frequency RF) chain (chain) unit (310-1 ~ 310- N _RF). The plurality of receivers 320-1 to 320-K may receive N _s streams through corresponding channels H ₁ ... H _K , where H _K denotes the channel of the Kth receiver.

On the other hand, it indicates the channel (H _k) of the k-th receiver, the total K receivers (320-1 ~ 320-K) in a form having an L number of signals (ray) as shown in the following equation (4).

은 k번째 수신기의 l번째 신호에 대한 이득(gain)을 나타내고,

는 k번째 수신기의 l번째 신호에 대한 AOD를 나타내고,

은 k번째 수신기의 l번째 신호에 대한 도래각(Angle of Arrival)(이하 'AOA'라 칭함)를 나타내고, H는 허미시안 연산을 나타낸다. 그리고 상기 수학식 4에서 어레이 벡터인 a _r (θ) 및 a _t (θ) 는 각각 다음 수학식 5 및 6에 나타난 바와 같이 균일 선형 배열(Uniform Linear Array: ULA) 형태로 구성될 수 있다. In Equation (4)

Represents the gain for the l < th > signal of the k < th > receiver,

Represents the AOD for the l < th > signal of the k < th > receiver,

Denotes an angle of arrival (AOA) for the l- th signal of the k- th receiver, and H denotes a Hermitian operation. In Equation (4), the array vectors a _r (?) And a _t (?) Can be formed in the form of a uniform linear array (ULA) as shown in the following equations (5) and (6 ) , respectively.

In Equations (5) and (6), d represents an antenna spacing and ? Represents a wavelength of a signal.

In the transmitter, the total number of stream signal s corresponding to the _{(N ts = N s ⅹ K} ): [N ts ⅹ1] The baseband precoder _{(baseband precoder) (F bb:} [N RF ⅹ N ts]) (300) And an RF chain portion ( F _RF : [ N _t x N _RF ]) 310-1 to 310- N _RF . The baseband precoder 300 and RF chain units 310-1 to 310- N _RF , which may be collectively referred to as a preprocessor, may be represented by a matrix. In the embodiment of the present invention, this is defined as a null steering beamformer ( F _null : [ N _t x N _ts ]) and expressed as Equation (7).

F _{k, 1} denotes a first stream to be transmitted to a kth receiver, f _{k, 2} denotes a second stream to be transmitted to a kth receiver, and f _{k and N s} are to be transmitted to a kth receiver N _{s &} lt; / RTI >

를 통해 하기 다음 수학식 8과 같은 수신 신호를 획득할 수 있다.When the transmitter transmits a signal of F _null to K receivers, the kth receiver receives a corresponding signal through a plurality of antennas,

The following equation (8) can be obtained.

In Equation (8), y _k denotes a received signal of the k- th receiver, and n _k denotes a noise received by the k- th user.

In the embodiment of the present invention, a method for performing interference control using the null control beamformer defined above is proposed. Hereinafter, the interference control method proposed in the embodiment of the present invention will be described in detail.

4 is a diagram illustrating a process in which a plurality of receivers according to an embodiment of the present invention transmit feedback information to a transmitter.

In FIG. 4, it is shown that the K receivers 420-1 to 420-K transmit AOD information as feedback information to a transmitter including the null adjusting beamformer 400, respectively. The K receivers (420-1 ~ 420-K) shown in Figure 4 may correspond to the K receivers (320-1 ~ 320-K) shown in Fig. The process of transmitting the feedback information will be described in detail as follows.

First, a kth receiver among the K receivers 420-1 to 420-K receives L signals from the transmitter, and estimates gains, AODs, and AOAs for the L signals. And the k-th receiver sorts the index for the L signals to the large gain in order for the L signal, and stores the index information according to the sort order. Here, the stored index information Q _k may be expressed by Equation (9).

Equation (9) shows that the indexes of L signals for the k- th receiver are arranged in order of increasing signal gain.

Based on the stored index information, the k < th > receiver also arranges the gains for the L signals with respect to the AOA in descending order, and forms a combiner for the k < th > receiver based on the sorted AOA information. The coupler may be constructed based on Equation (10).

는 상기 k번째 수신기가 수신한 신호에 대한 AOA를 나타낸다.In Equation (10), W _{k, i} represents a combined signal for signals (e.g., N _S streams) received by the kth receiver through a plurality of antennas, a _r () represents an array vector,

Represents the AOA for the signal received by the k < th > receiver.

The k < th > receiver then aligns the AOD with the gains for the L signals in descending order. The kth receiver feeds back the aligned AOD information to the transmitter. Here, the feedback AOD information is expressed by the following equation (11).

는 상기 k번째 수신기가 피드백하는 AOD 정보를 나타내고, B는 상기 k번째 수신기가 피드백하는 AOD 정보의 개수를 나타낸다

. 상기 L개의 신호 전체에 대한 AOD 정보가 피드백되면 피드백량이 많아지게 되므로, 상기 B는 통신 환경에 따라 다양하게 조정될 수 있다. In Equation (11)

Represents the AOD information fed back by the k- th receiver, and B represents the number of AOD information fed back by the k- th receiver

. If the AOD information for all of the L signals is fed back, the amount of feedback increases. Therefore, the B can be variously adjusted according to the communication environment.

When the AOD information is fed back from all of the K receivers 420-1 to 420-K, the transmitter can determine a null adjustment vector for the i- th stream of the k- th receiver using the feedback AOD information.

이고 m > 1이면, 널에 대한 어레이 벡터는

와 같이 나타낼 수 있다. 그러면 상기 송신기는 어레이 벡터들로 구성된 행렬 N _k,i 를 다음 수학식 12와 같이 나타낼 수 있다.First, a matrix N _{k, i} ( m ) composed of array vectors is defined as representing an m- th column vector of N _{k, i} , and an array vector

And m > 1, then the array vector for null is

As shown in Fig. Then, the transmitter can represent a matrix N _{k, i} composed of array vectors as shown in Equation (12).

Then, the transmitter may _calculate the null adjustment vector using N _{k, i} based on Equations (13) to (15), and finally determine the transmission power.

If the above process is performed, the result shown in FIG. 5 may be displayed.

5 is a graph illustrating transmission power of a transmitter according to a transmission direction according to an embodiment of the present invention.

Referring to FIG. 5, the array vector N _{k, i} (1) 520 for the transmission direction has the largest transmission power, and an array vector N _{k , i} ( m ) 500 has the smallest transmit power (for example, the transmit power is set to zero).

의 크기가 커져 정규화로 인한 성능 열화 현상이 나타남을 의미한다. 이를 방지하기 위해 N _k,i 구성 시 상관(correlation) 값이 어레이 벡터를 제외시키는 방안이 필요하다. 이를 위해 본 발명의 실시 예에서는 하기 수학식 16을 사용한다. On the other hand, if a similar array vector (that is, an array vector having a similar direction) exists in the process of calculating the null adjustment vector, the minimum eigen-value of N _{k, i} becomes very small. This is because the maximum eigen-value is diverted during calculation of the pseudoinverse N _{k, i} ⁺

And the performance degradation due to the normalization occurs. In order to prevent this _, it is necessary to exclude the array vector from the correlation value in the N _{k, i} configuration. For this purpose, the following expression (16) is used in the embodiment of the present invention.

Equation (16) indicates that when a new null vector is determined, the correlation value is compared with an array vector previously configured, and the corresponding array vector is used when the correlation value is lower than a specific threshold value.

가 결정되면, 널 조정 벡터의 특성에 따라 각 벡터의 엘리먼트(element)의 크기가 서로 비슷한 크기의 범위를 가짐을 알 수 있다. 이러한 특성을 기반으로 널 조정 빔포머(F _null )를 하이브리드(hybrid) 빔포밍 시스템에 적용하기 위해 하기 수학식 17 내지 19가 사용될 수 있다.On the other hand, the null adjustment vector

It can be seen that the sizes of the elements of each vector have a similar size to each other according to the characteristics of the null adjusting vector. Based on this characteristic, the following equations (17) to (19) can be used to apply a null adjusting beam former ( F _null ) to a hybrid beam forming system.

Since the RF chain portion of the transmitter includes a phase shift, the elements in the RF chain portion can not have a size. Therefore, as shown in Equation (17), the RF chain portion F _RF may be configured to include elements based on the phase component of the _null adjusting beamformer ( F _null ).

And the baseband precoder F _BB may include elements determined by performing a pseudoinverse matrix operation of a matrix including the elements of the RF chain portion, as shown in Equation (18) above. This method can be applied because elements of the null adjustment vector have similar size values. In fact, it can be confirmed that elements of the diagonal matrix type are included in the baseband precoder.

As a result, the RF chain portion F _RF and the baseband precoder F _BB may include elements similar to the _null adjusting beamformer F _null as shown in Equation 19 above. This is shown in FIG. 6 as a drawing.

FIG. 6 is a diagram illustrating a baseband precoder and RF chain unit constructed based on a null adjusting beam former in accordance with an embodiment of the present invention. As shown in FIG. 6, the baseband precoder 620 and the RF chain portion 640 may include elements similar to the null adjusting beamformer 600. When such a configuration is used, the number of RF chains may be reduced by the total number of streams smaller than the number of antennas.

Next, operations of the transmitter and the receiver according to the embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIG.

7 is a flowchart illustrating an operation of a receiver according to an embodiment of the present invention.

Referring to FIG. 7, in step 700, the receiver receives L signals from a transmitter. In step 702, the receiver estimates gains, AOAs, and AODs for the L signals.

In step 704, the receiver arranges and stores index information on the L signals in order of increasing signal gain. In step 706, the receiver aligns the AOAs in a descending order of the signal gains based on the stored index information, and combines the received signals.

In step 708, the receiver aligns the AODs in descending order of the signal gain based on the stored index information, and feeds back information on the aligned AODs to the transmitter.

8 is a flowchart illustrating an operation of a transmitter according to an embodiment of the present invention.

Referring to FIG. 8, in step 800, the transmitter receives AOD information arranged in order of increasing signal gain from K receivers. In step 802, the transmitter constructs an array matrix for each stream of the K receivers.

In step 804, the transmitter compares the correlation value of the vectors constituting the array matrix with a threshold value. If the correlation value is smaller than the threshold value in step 806, the transmitter proceeds to step 808 and calculates a null adjustment vector for each stream of the K receivers.

In step 810, the transmitter determines a radio processing operation using the phase component of the null control vector. In step 812, the transmitter determines a baseband processing operation based on the null adjustment vector and the wireless processed vector, and transmits a signal according to the determined baseband processing operation and radio processing operation in step 814.

9 is a graph illustrating performance according to an interference control method according to an embodiment of the present invention.

)를 가지며, AOD(

)의 분포는 각 수신기의 중심 각도(θ _k )에서 균등 분포(uniform distribution)

를 갖도록 한다. 그리고 AOA(

)의 분포는 채널의 산란(scattering) 특성에 의해 결정되므로,

로 설정된 경우 신호의 개수는 4~10개 사이로 발생시켜 그 성능을 살펴보았다. The channel environment for examining the effects according to the embodiment of the present invention is a channel-based channel structure with a strong line-of-sight (LOS)

), And AOD (

) Is a uniform distribution at the center angle ( ? _K ) of each receiver,

. And the AOA (

) Is determined by the scattering characteristics of the channel,

The number of signals is generated between 4 and 10, and the performance is examined.

Referring to FIGS. 9A and 9B, since the interference is not considered when the beam adjusting method is used, the sum rate is gradually increased as the SNR is increased (see the beam steering graph) .

In addition, interference cancellation is effective at a high SNR when a general null control method considering interference is used. However, it can be seen that performance degradation occurs in the process of normalizing power of a preprocessor (see Null steering graph).

Using the correlation-based null adjustment method according to the embodiment of the present invention in which this is taken into account can reduce the performance degradation phenomenon (see Null steering (corr) graph).

On the other hand, if the above-mentioned null adjustment method is a base band-based null adjustment method and the null adjustment method is applied to a hybrid beam forming system, the number of RF chains is about 64 (number of antennas) to 8 (Number of users). Here, performance degradation due to approximation may exist, but interference cancellation effect can be seen to some extent.

 As compared with FIG. 9A, the null adjustment method can have a higher performance in an environment where the number of feedback signals is larger as shown in FIG. 9B, and the advantage that the performance gain due to the correlation-based selection method also increases .

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various modifications within the scope of the invention. Therefore, the scope of the present invention should not be limited by the illustrated embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

Claims (20)

A method of transmitting a signal in a transmitter in a wireless communication system,
Transmitting a plurality of signals to a receiver using a plurality of antennas,
Determining a signal transmission direction based on the angle of departure information when at least one of the plurality of signals is received from the receiver;
Transmitting a signal using a predetermined transmission power in the determined signal transmission direction;
And performing null transmission in a signal transmission direction other than the determined signal transmission direction,
Wherein the launch angle information comprises launch angle information for at least one of the plurality of signals arranged in descending order of signal gain. The method according to claim 1,
The process of performing the null transmission includes:
And setting transmission power in the remaining signal transmission direction to zero. The method according to claim 1,
Wherein the determining of the signal transmission direction comprises:
And determining the signal transmission direction based on emission angle information of a signal having a largest signal gain among the plurality of signals. The method according to claim 1,
Wherein the determining of the signal transmission direction comprises:
Determining an array matrix for the plurality of signals;
Calculating a correlation value between vectors included in the array matrix;
And determining the signal transmission direction based on the calculated correlation value. 5. The method of claim 4,
Wherein the step of determining the signal transmission direction based on the calculated correlation value comprises:
Comparing the calculated correlation value with a threshold value;
Removing at least two of the vectors from the array matrix based on the comparison result;
And determining the signal transmission direction based on an array matrix excluding the at least two vectors. 5. The method of claim 4,
Calculating a correlation value between vectors included in the array matrix,
And calculating a correlation value between vectors corresponding to signals allocated to directions adjacent to each other among vectors included in the array matrix. The method according to claim 1,
Wherein the determining of the signal transmission direction comprises:
Detecting a second direction adjacent to the first direction among the plurality of signal transmission directions,
Calculating a correlation value of a signal assigned to the first direction and a signal assigned to the second direction;
And determining to use the second direction as a signal transmission direction according to whether the calculated correlation value is smaller than a predetermined value. The method according to claim 1,
The process of transmitting the signal includes:
And transmitting the signal using a baseband precoder and a radio frequency chain unit,
Wherein the radio frequency chain unit performs a radio processing operation based on phase information of a null control vector determined for each receiver,
The baseband precoder performs a baseband precoding operation based on the null adjustment vector and vector information for radio processing,
Wherein the null adjustment vector indicates an array vector according to signal transmission direction and direction information on which null transmission is to be performed. The method according to claim 1,
The process of transmitting the signal includes:
And transmitting the signal using a null adjusting beamformer,
Wherein the null adjusting beam former performs a baseband precoding operation based on a null adjustment vector determined for each receiver and vector information for radio processing and a radio processing operation based on phase information of the null adjustment vector,
Wherein the null adjustment vector indicates an array vector according to signal transmission direction and direction information on which null transmission is to be performed. The method according to claim 1,
Wherein the largest transmission power is used in the determined signal transmission direction and the smallest transmission power is used in the remaining signal transmission direction. A transmitter in a wireless communication system,
A plurality of antennas,
A transmitter for transmitting a plurality of signals to the receiver using the plurality of antennas,
A receiving unit for receiving angle of departure information for at least one of the plurality of signals from the receiver;
Determines a signal transmission direction based on the emission angle information, and controls the transmission unit to transmit a signal using a predetermined transmission power in the determined signal transmission direction, null) transmission,
Wherein the launch angle information comprises launch angle information for at least one of the plurality of signals arranged in order of increasing signal gain. 12. The method of claim 11,
Wherein the control unit sets the transmission power in the remaining signal transmission direction to zero. 12. The method of claim 11,
Wherein the controller determines the signal transmission direction based on emission angle information of a signal having a largest signal gain among the plurality of signals. 12. The method of claim 11,
Wherein the controller determines an array matrix for the plurality of signals, calculates a correlation value between vectors included in the array matrix, and determines the signal transmission direction based on the calculated correlation value. . 15. The method of claim 14,
Wherein the control unit compares the calculated correlation value with a threshold value, excludes at least two of the vectors from the array matrix based on the comparison result, and determines, based on the array matrix excluding the at least two vectors, And determines a direction of signal transmission. 15. The method of claim 14,
Wherein the controller calculates a correlation value between vectors corresponding to signals allocated to directions adjacent to each other among vectors included in the array matrix. 12. The method of claim 11,
Wherein the controller detects a second direction adjacent to a first direction among a plurality of signal transmission directions and calculates a correlation value between signals assigned to the first direction and the second direction, And determines to use the second direction as a signal transmission direction depending on whether the first direction is small or not. 12. The method of claim 11,
Further comprising a baseband precoder and a radio frequency chain portion,
Wherein the radio frequency chain unit performs a radio processing operation based on phase information of a null control vector determined for each receiver,
The baseband precoder performs a baseband precoding operation based on the null adjustment vector and vector information for radio processing,
Wherein the null adjustment vector represents an array vector according to signal transmission direction and direction information on which null transmission is to be performed. 12. The method of claim 11,
Further comprising a null adjusting beamformer,
Wherein the null adjusting beam former performs a baseband precoding operation based on a null adjustment vector determined for each receiver and vector information for radio processing and a radio processing operation based on phase information of the null adjustment vector,
Wherein the null adjustment vector represents an array vector according to signal transmission direction and direction information on which null transmission is to be performed. 12. The method of claim 11,
Wherein the largest transmission power is used in the determined signal transmission direction and the smallest transmission power is used in the remaining signal transmission direction.

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